This works for me around 95% of the time meaning I don't miss out on the first few most profitable days of a video. If you've got a yellow icon, go to the mobile app, edit your scheduled video and download the thumbnail. The thumbnail filename should be a date, not the original filename you uploaded. Don't change it back! Log into your account on your mobile browser, make sure you have 'show desktop version' of the site, and then find the video and edit it in creator studio. Re-upload the thumbnail with the new filename from your mobile device. Give it a few minutes and your video should now have the green icon. Like I said, for scheduled videos that get yellow icons straight way this works more than 95% of the time, so they are green for launch. Interested to see if it works for anyone else!